PubMed Health⌕ Search

Biomedical subjects

D De Medici

Publications and source records attributed to D De Medici.

At least 19 recordsLinked to original sources
PubMed2002

Detection of hepatitis A virus in mussels from different sources marketed in Puglia region (South Italy).

Hepatitis A virus (HAV) infection is endemic in Puglia (South Italy). Epidemiological studies indicate that shellfish consumption, particularly mussels, is a major risk factor for HAV infection, since these products are eaten raw or slightly cooked. Nested reverse transcriptase-polymerase chain reaction (RT-PCR) has been shown to be a sensitive technique for the detection of HAV in mussels. The aim of the present study was to detect the presence of HAV in a large sample of mussels by nested RT-PCR and to confirm the presence of infectious viral particles in positive samples by cell culture infection and RT-PCR confirmation. Two hundred and ninety samples of mussels from different sources were collected between December 1999 and January 2000. One hundred samples were collected before being subjected to depuration, 90 after depuration, and 100 were sampled in different seafood markets. HAV-RNA was detected in 20 (20.0%) of non-depurated mussels, in 10 (11.1%) of depurated samples, and in 23 (23.0%) of samples collected in the shellfish markets, without any significant difference in the prevalence of positive samples by collection sources (chi2 = 4.79, p = 0.09). Of the 53 samples found positive by nested RT-PCR, 18 (34.0%) resulted positive by cell culture assay. No relationship between viral contamination and bacterial contamination was found (p = 0.41). This study confirms the usefulness of molecular techniques in detecting HAV in shellfish and, thus, for the screening of a large sample of naturally contaminated mussels. Improved shellfish depuration methods are needed to obtain virus-safe shellfish and reduce the risk for public human health.

Animals↗
PubMed2001

Detecting the presence of infectious hepatitis A virus in molluscs positive to RT-nested-PCR.

AIMS: The objective of this study was to determine the presence of infectious hepatitis A virus (HAV) in molluscs naturally contaminated with viral HAV-RNA. METHODS AND RESULTS: One hundred and forty-two mollusc samples were analysed for the presence of viral HAV-RNA using RT-nested-PCR; positive samples were then analysed with an integrated method, cell-culture RT-PCR, to detect infectious virus. Viral HAV-RNA was detected in 34.5% of the samples while 12.7% of the total samples were positive for the presence of infectious virus. CONCLUSIONS: The results demonstrate the validity of the screening method (RT-nested-PCR) and the necessity of applying a method that is capable of detecting the presence of infectious HAV. SIGNIFICANCE AND IMPACT OF THE STUDY: The study demonstrates that in any case, to determine the safety for human consumption, the results of RT-nested-PCR must be confirmed with an integrated cell-culture PCR method.

Animals↗
PubMed2001

Closed-circuit system for the depuration of mussels experimentally contaminated with hepatitis A virus.

In Italy, the consumption of raw or slightly cooked mussels represents the most important risk factor for the transmission of hepatitis A virus (HAV). Although there exist effective methods for the bacterial depuration of contaminated mussels, these methods are poorly effective on enteric viruses. The objective of the present study was to evaluate the effectiveness of a closed-circuit depuration system that uses both ozone and UV light for disinfecting water and that allows salinity and temperature, important parameters for the metabolism of mussels (Mytilus galloprovincialis), to be maintained at constant levels. The results showed that this depuration method decreased the viral load (from 1.72 log 50% tissue culture infective dose [TCID50] ml(-1) to <1 log TCID50 ml(-1) within 24 h and from 3.82 log TCID50 ml(-1) to <1 log TCID50 ml(-1) within 48 h). However, in both cases, after 120 h of depuration, a residual amount of virus capable of replicating in cells was detected. These results show that depuration, even if performed with advanced systems, may not guarantee the absence of virus.

Animals↗
PubMed2000

Determination of enteroviruses, hepatitis A virus, bacteriophages and Escherichia coli in Adriatic Sea mussels.

The aim of the present study was to evaluate the incidence of enteric viruses in mussels and to verify the possibility of using phages as indirect indicators of mussel viral contamination. Mussels (36 samples) collected from three different areas of the Adriatic Sea were analysed to determine the following parameters: Escherichia coli, somatic coliphage (T6 phage), F-Plus (MS2 phage), B40-8 (phage of Bacteroides fragilis), enteroviruses and hepatitis A virus. Most of the results of the bacteriological analysis (most probable number (MPN) ml-1) were in accordance with the bacteriological limits established by European law, with the exception of seven samples. The bacteriophage analyses were always negative for F-Plus and B40-8, with the exception of a few samples, whereas the somatic coliphages were generally between 0 and 20 MPN g-1, with the exception of two samples (110 MPN g-1). The virological analysis showed five samples positive for the presence of enteroviruses and 13 for the presence of hepatitis A virus (in three samples both viruses were present). Most of these samples presented acceptable bacteriological parameters and the bacteriophages were absent or their value was generally very low. The results show that the detection of E. coli and phages does not seem to be a good indicator of viral contamination.

Animals↗
PubMed1999

Detection of hepatitis A virus in shellfish by nested reverse transcription-PCR.

A method for the detection of HAV in shellfish, based on the use of guanidinium isothiocyanate-containing solution for RNA extraction and purification steps, followed by nested PCR, is hereby proposed. Tests were carried out on mollusc samples spiked with HAV strain FG. Results showed that in samples subjected only to one round of PCR it was possible to detect HAV at concentrations of 10(3)-10(4) TCID50/10 g of mollusc. The use of the nested PCR renders the system more sensitive and specific enabling the identification of HAV concentrations as low as 1 TCID50/10 g of mollusc. Furthermore thus method, in addition to allowing the avoidance of confirming tests, such as hybridization, proved to be inexpensive and simple to perform.

Animals↗
PubMed1999

Inactivation of hepatitis A virus in heat-treated mussels.

Hepatitis A is a widespread infectious disease world-wide. In Italy, shellfish consumption was shown to be a major risk factor for hepatitis A infection, especially when these products are eaten raw or slightly cooked. The aim of the present study was to evaluate Hepatitis A virus (HAV) resistance in experimentally contaminated mussels treated at different temperatures (60, 80 and 100 degrees C) for various times. The presence of HAV was evaluated by cell culture infection and reverse transcriptase-polymerase chain reaction confirmation. The experiments, carried out on HAV suspension and contaminated mussel homogenate both containing about 10(5) 50% tissue culture infectious dose ml-1, showed that, under our experimental conditions, the treatments at 60 degrees C for 30 min, 80 degrees C for 10 min and an immersion at 100 degrees C for 1 min were not sufficient to inactivate all the viruses; it was necessary to prolong the treatment at 100 degrees C for 2 min to completely inactivate the virus. Thus it is advisable to eat only cooked shellfish, paying particular attention to the times and temperatures used in the cooking process, since evidence suggests that the shellfish body may protect the virus from the heat effect.

Animals↗
PubMed1998

Comparison between ICS-Vidas, MSRV and standard cultural method for Salmonella recovery in poultry meat.

Two rapid methods for Salmonella detection, Vidas-ICS and modified semi-solid Rappaport-Vassiliadis (MSRV) were evaluated using contaminated poultry meat. The sensitivity and specificity of the methods were investigated on field samples and on artificially contaminated samples inoculated with mixtures of Salmonella and non-Salmonella competing strains. ICS-Vidas and MSRV yielded virtually identical results, in full agreement with the standard cultural method (SCM). The MSRV method showed better results with artificially contaminated samples, but was less sensitive than SCM when applied to field samples. The use of the MSRV and Vidas-ICS methods could be particularly advantageous in the application of HACCP.

Animals↗
PubMed1998

Application of reverse transcriptase-nested-PCR for detection of poliovirus in mussels.

In order to identify polioviruses in molluscs, we hereby propose a method based on precipitation with PEG 6000 followed by the use of a commercial kit (RNAfast II-Molecular System-San Diego) for the extraction and purification of viral RNA. The RT-PCR phase is followed by a second amplification using nested primers to increase the sensitivity and specificity of the method. Tests were carried out on mollusc samples spiked with Poliovirus 1. Results showed that in samples subjected only to one round of PCR it was possible to detect Poliovirus concentrations as small as 10(3)TCID50/ml. The use of nested-PCR makes the system more sensitive and specific enabling the identification of Poliovirus concentrations as small as 1 TCID50/ml.

Animals↗
PubMed1997

A rapid tissue culture assay for the detection of okadaic acid and related compounds in mussels.

Okadaic acid, the main toxin of the diarrhoetic shellfish poisoning (DSP) group, shows high cytotoxicity to Buffalo green monkey (BGM) kidney cell cultures after different times according to concentration. A rapid method of detecting the presence of okadaic acid and related compounds in contaminated mussels by means of a cytotoxicity test is presented. The method is based on direct microscopic observation of toxin-induced morphological changes in BGM cell cultures. A high correlation (r = 0.950; P < 0.001) was found between the official mouse bioassay and the cytotoxicity test conducted on naturally contaminated samples of Mytilus galloprovincialis.

Animals↗
PubMed1994

Comparison of mouse bioassay, HPLC and enzyme immunoassay methods for determining diarrhetic shellfish poisoning toxins in mussels.

Mussel specimens (Mytilus galloprovincialis) collected from two different areas of the Adriatic Sea were analysed for diarrhoetic shellfish poisoning (DSP) toxin by three methods: mouse bioassay, the DSP Check enzyme immunoassay kit, and high-performance liquid chromatography (HPLC). The results obtained confirm that Yasumoto's mouse bioassay, capable of detecting all the components of the DSP group, is still necessary to determine the wholesomeness of the product. The ELISA method has not always given quantitatively reliable results. The HPLC method is advantageous in terms of sensitivity, accuracy, specificity and rapidity. However, its application is limited so far to the determination of okadaic acid in mussels.

Animals↗
PubMed1994

Diarrhetic shellfish poison in mussels: comparison of methods of detection and determination of the effectiveness of depuration.

The lack of specificity of the Yasumoto mouse bioassay for Diarrhetic Shellfish Poisoning (DSP) toxin and the possibility of obtaining false positive results, prompted a search for a suitable method to confirm doubtful results. The mouse bioassay, an enzyme-linked immunoassay (ELISA) and a tissue culture bioassay were compared; in addition the efficiency of depuration of toxic mussels in ozonized water was evaluated. DSP assay using tissue cultures was found suitable for confirming results obtained using the mouse bioassay, particularly where interpretation was difficult. The ELISA kit gave satisfactory results, but it responded only to okadaic acid and dinophysistoxin 1. Depuration reduced toxicity in some cases after 3 days of treatment.

Animals↗
PubMed1990

Relative efficacies of benzodiazepine receptor agonists in affecting red nucleus electrical activity in rabbits.

The effects of benzodiazepine receptor agonists on the electrical activity of red nucleus (RN) and neocortex were studied in rabbits. Under basal conditions, 30-40 microV, 40-50 Hz waves were recorded in RN. An increase of the amplitude (Emax, 75-90 microV) was found after IV injection of flunitrazepam (ED50, 0.14 mg/kg), diazepam (ED50, 0.28 mg/kg), alpidem (ED50, 1.57 mg/kg) and zolpidem (ED50, 0.73 mg/kg). Clonazepam (ED50, 0.12 mg/kg) and Cl 218,872 (ED50, 0.63 mg/kg) were less effective. In contrast, 2-10-fold higher doses were required to induce a slight decrease of the frequency. At the level of the cortex all benzodiazepine agonists induced synchronization and spindles. The effects of diazepam (5 mg/kg IV) in both areas were antagonized by flumazenil (0.04 mg/kg IV) and bicuculline (0.2 mg/kg IV). Pentamethylentetrazole (10-30 mg/kg IV) selectively abated the effect at the level of the cortex, whereas both clonazepam (2 mg/kg IV) and beta-CCM (0.6 mg/kg IV) selectively suppressed only the effects on the RN. These results suggest that activation of benzodiazepine receptor mainly influences the RN waves amplitude. The efficacy in increasing the amplitude appears related to the reported relative efficacy of the compound in potentiating GABA responses. The possibility exists that these effects are dependent upon the partial or full agonist action of the drugs or upon their binding at distinct benzodiazepine receptor types.

Animals↗
PubMed1990

Depuration of Mytilus galloprovincialis experimentally contaminated with hepatitis A virus.

Mussels (Mytilus galloprovincialis) were contaminated with known amounts of laboratory strains of hepatitis A virus and Poliovirus 1 and the effectiveness of a self-cleansing mechanism was studied using a pilot depuration system. Both viruses were rapidly bioaccumulated by mussels and the maximal concentration of about 10(4) TCID50/ml was reached within 1.5 hours. Depuration was carried out up to 24 h; infectivity titer decreased to 10(2) TCID50/ml and 10(3.2) TCID50/ml within 6 h in hepatitis A virus and Poliovirus 1 contaminated mussels, respectively, but only a very slight further decrease was obtained after 24 h. E. coli was used as a control; within 24 h the concentration decreased from 40 to 2 bacteria/ml of mussel (MPN). The elimination of bacteria is not a reliable parameter to control the effectiveness of viral depuration.

Animals↗